Hough transform-based approach for estimating 3D rotation angles of vertebrae from biplanar radiographs using GPU-acceleration.

ABSTRACT For scoliosis assessment, a system was developed to estimate the three-dimensional (3D) rotation angles of vertebrae from biplanar radiographs. The proposed approach was based on the generalized Hough transform (GHT) technique to match the projected contours of the standard 3D primitive with vertebral edges detected in biplanar radiographs. A deformation tolerant matching strategy was proposed to extend the GHT for an inexact contour matching. The system was implemented on a graphics processing unit (GPU). Seventeen dry vertebral specimens were used to evaluate accuracy. Precision was tested by three operators on 181 vertebrae from radiographs of 15 patients. With GPU computing, the average estimation time was 10 s for a vertebra. Results showed that the 3D estimation error was less than 2.5° with the mean value of 1.6°. The intraoperator variability was within 1.6° and the interoperator variability was within 2.2°. These promising results indicate that the proposed system can help orthopedic surgeons measure the 3D vertebral rotation angles from two-dimensional radiographs for better assessment of scoliosis. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 272-279, 2013 [ABSTRACT FROM AUTHOR]